Frequency multiplier for fluid state systems



July 22, 1969 H. L. WHEELER, JR 8 FREQUENCY MULTIPLIER FOR FLUID STATE SYSTEMS Filed Sept. 16, 1966 INVENTOR HARRY L. WHEELER JR.

ATTORNEY "United States Patent 3,456,668 7 FREQUENCY MULTIPLIER FOR FLUID STATE SYSTEMS Harry L. Wheeler, Jr., Dunwoody, Ga., assignor to The Bendix Corporation, a corporation of Delaware Filed Sept. 16, 1966, Ser. No. 580,081 Int. Cl. Fc 1/08; F15d 1/14 U.S. Cl. 13781.5 1 Claim ABSTRACT OF THE DISCLOSURE A frequency multiplier for fluid systems having a pair of fluid chambers separated by a flexible diaphragm having a given natural frequency in combination with a fluid oscillator for pulsing the fluid in one of the chambers at a rate below the natural frequency of the diaphragm to cause the diaphragm to oscillate at its natural frequency.

This invention relates generally to the art of fluidics and more particularly to an improved frequency multiplier for fluid state systems.

The frequencies achievable in fluid state systems, with the equipment presently available, are limited to frequencies below those that are sometimes desirable. For example, frequencies are presently limited to about ten thousand cycles per second or less and higher frequencies are often useful, particularly in sonic devices, such as sonar, transducers. Higher frequencies could also be useful in certain fluid filter environments. It is an object of this invention, therefore, to provide an improved frequency multiplier for fluid state systems which is capable of developing higher frequencies.

In the frequency multiplier of this invention, a pair of fluid chambers are separated by a thin flexible diaphragm having a predetermined natural frequency. When the fluid in one of the cavities is pulsed at a given frequency less than the natural frequency of the diaphragm, pressure pulsations will be transmitted to the other cavity at a frequency corresponding to the natural frequency of the diaphragm. Standing waves will be created in the second cavity which will be typical of the natural frequency of the diaphragm. As a result, the frequency of pulsations in the fluid in the second cavity will be multiplied relative to the frequency of the pulses transmitted to the first cavity. If the diaphragm is oscillated at one of its natural harmonics, the multiplication of the frequency of the pulses in the first cavity is even greater.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

FIGURE 1 is a diagrammatic view illustrating one form of the frequency multiplier of this invention.

With reference to the drawing, the frequency multiplier of this invention, indicated generally at 10, is illustrated in the drawing as consisting of a body 12 having a thin flexible diaphragm 14 fixedly mounted at 16 thereon so as to form a pair of chambers A and B in the body 12 on opposite sides of the diaphragm 14. A fluid oscillator, indicated generally at 18, is connected to the body 12 so that it communicates with chamber A through inlet ports and 22. The fluid oscillator 18 can be of any suitable construction, and is illustrated herein as consisting of a pump 24 capable of supplying a jet of fluid to either one of a pair of receiver passages 26 and 28 which terminate in the inlet ports 20 and 22, respectively. A feedback line communicates at one 3,456,668 Patented July 22, 1969 of its ends with the passage 26 and at its opposite end with a control port 32. A similar feedback passage 34 communicates at one end with the receiver passage 28 and at the opposite end with a control port 36.

A jet of fluid issuing from the pump 24 will adhere to one or the other of the passages 26 and 28 depending upon the flow of fluid at the control ports 32 and 36. For example, with the jet adhering to the passage 26, a portion of the jet flow will travel through the feedback passage 30 and through the control port 32 so as to flip the jet into the passage 28. This will result in a portion of the jet fluid flowing through the feedback passage 34 into the control port 36. Fluid issuing from control port 36 will in turn cause the jet to flip back to the passage 26. The result is an oscillation of the jet back and forth between the inlet ports 20 and 22 so as to pulse the fluid in chamber A at a certain frequency dependent upon the construction of the oscillator 18. In the illustrated embodiment of the invention, chamber A has an outlet port 38 which communicates with the inlet for the pump 24 through a passage 40 so that a continuous pulsing of the fluid in the chamber A is obtained.

This excitation of the fluid in chamber A by the jet from the oscillator 18 causes vibration of diaphragm 14. A diaphragm 14 is selected which has mass and elastic constants such that the natural frequency of the diaphragm 14 is a whole number multiple of the frequency of the pulses created in chamber A by the fluid oscillator 18. The oscillator 18 can also be selected and adjusted relative to a known natural frequency for the diaphragm 14 to achieve this condition. As a result, in the multiplier of this invention:

where j =output frequency in chamber B f =input frequency in chamber A n=a whole number.

For example, assume that the diaphragm 14 has a natural frequency of 2F and that the fluid in chamber A is excited through the fluid oscillator 18 to a frequency F. This will cause the fluid in chamber B to be pulsed at a frequency of 2F, and standing Waves will be set up in chamber B which are typical of the 2F frequency of the diaphragm 14. Thus, the device 10 will function as a step up frequency transformer. If the diaphragm 14 is caused to vibrate at one of its natural harmonics, the degree of step up will of course be further increased.

The chamber B is illustrated as having an inlet 42 and an outlet 44, the fluid from outlet 44 being pulsed at a frequency higher than that heretofore achievable so that it can be used in, for example, a sonar transducer. It is also possible to use the apparatus 10 for filtering the fluid in either chamber A or chamber B since the standing waves created therein will cause accumulations of solid particles in the fluids at locations where the particles can readily be removed.

It will be understood that the frequency multiplier for fluid state systems which is herein disclosed and described is presented for purposes of explanation and illustration, the scope of which is defined by the following claim:

1. A frequency multiplier for fluid systems comprising means forming a pair of fluid chambers, a flexible diaphragm mounted in a position separating said chambers and having a natural frequency, means for pulsing the fluid in one of said chambers at a predetermined frequency to thereby oscillate said diaphragm, said diaphragm natural frequency being a whole number multiple, greater than one, of said predetermined frequency so 4- that the fluid in said second chamber is pulsed at 21 3,260,456 7/1966 Boothe 13781.5 XR frequency greater than said predetermined frequency 3,275,015 9/1966 Meier 137--8.15

3,318,329 5/1967 Norwood.

References Cited OTHER REFERENCES UNITED STATES PATENTS 5 Fluid Actuated Latch, F. R. Humphreys et aL, I.B.M. 862,867 8/1907 Eggleston 25161.1 XR Technical Disclosure Bulletin, vol. 8, No. 3, August 1965, 3,124,999 3/1964 Woodward 137--81.5 XR pp. 427, 428. 3,144,037 8/1964 Cargill et al. 137815 3,202,179 8/1965 Vockroth 137-815 XR SAMUEL SCOTT, Primary Examiner 

